幾何学コロキウム：On the Falk Invariant of Shi-arrangement　（Weili Guo氏，北海道大学）

開催日時

2019年5月17日 16時30分 ～ 2019年5月17日 18時00分

場所

理学部３号館３－２０４室

講演者

Weili Guo （北海道大学）

Title: On the Falk Invariant of Shi-arrangement.

Abstract: It is an open question to give a combinatorial interpretation of the Falk invariant of a hyperplane arrangement, i.e. the third rank of successive quotients in the lower central series of the fundamental group of the arrangement. In this article, we give a combinatorial formula for this invariant in the case of hyperplane arrangements that are complete lift representation of certain gain graphs. As a corollary, we compute the Falk invariant for the cone of Shi, Linial and semiorder arrangements.